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Format of Extended BIOS Data Area (see 40:0Eh for ptr) [PS only]
Offset  Size    Description
 00h    BYTE    Length of EBDA in kilobytes
 01h 15 BYTEs   reserved
 17h    BYTE    Number of entries in POST error log (0-5)
 18h  5 WORDs   POST error log (each word is a POST error number)
 19h-21h        reserved
 22h    DWORD   Pointing Device Driver entry point
 26h    BYTE    Pointing Device Flags 1
                   bit 7:    =1 command in progress
                   bit 6:    =1 resend
                   bit 5:    =1 acknowledge
                   bit 4:    =1 error
                   bit 3:    =0 reserved
                   bits 2-0: index count
 27h    BYTE    Pointing Device Flags 2
                   bit 7:    =1 device driver far call flag
                   bits 6-3: reserved
                   bits 2-0: package size
 28h  7 BYTEs   Pointing Device Auxiliary Device Data
 2Fh    BYTE    reserved
 30h    DWORD   Vector for INT 07h stored here during 80387 interrupt
 34h    DWORD   Vector for INT 01h stored here during INT 07h emulation
 38h    BYTE    Scratchpad for 80287/80387 interrupt code
 39h    WORD    Timer3: Watchdog timer initial count
 3Bh    BYTE    ??? seen non-zero on Model 30
 3Ch    BYTE    ???
 3Dh 16 BYTEs   Fixed Disk parameter table for drive 0 (oh really?)
 4Dh 16 BYTEs   Fixed Disk parameter table for drive 1 (oh really?)
                    Neither of above seen on any Model 30, 50, 60 yet.
 5Dh-6Bh        ???
 6Ch    BYTE    Fixed disk: (=FFh on ESDI systems)
                    bits 7-4: Channel number 00-0Fh
                    bits 3-0: DMA arbitration level 00-0Eh
 6Dh and up:    ??? seen non-zero on Model 60
3F0h    BYTE    Fixed disk buffer (???!!!)